Systems for the diagnosis of communication connections are known such as, for example, systems known from the Ethernet field which analyze copper wires or optical fiber connections, hereinafter also designated as FO (fiber optic) connections, for packet lengths, number of incorrect data packets or other variables and make the data available via a suitable diagnosis interface such as, for example, an integrated web server or SNMP (Simple Network Management Protocol). Such systems are also used, for example, for the diagnosis of Bluetooth radio connections, wherein typically not only errors are evaluated, but also information about receiving and transmitting power of the communication signals is possible.
From DE 101 19 151 A1, for example, a diagnosis device for a field bus with control-independent information transfer is known, wherein the transfer of diagnosis data takes place via the PLC I/O bus and the interfaces present in the PLC (Programmable Logic Controller).
All such systems are limited—as in the case of the Ethernet diagnosis—to purely counting the errors or, as in the case of the Interbus FO diagnosis and the Bluetooth radio diagnosis, allow to draw anticipatory conclusions about errors still to come or causes of errors already occurred.
All systems have in common that with respect to the limit values for the diagnosis data necessary for an error-free operation of the communication connection, they are exclusively based on real “worst case” limit values which define the extent of the deviation of a variable from the normal state at which deviation the function of the system is not yet at risk. Within the worst case limit values for certain measured variables or from variables derived from said measured variables, thus, typically, an error-free function of the respective system is ensured.
Certain errors such as, for example, poor connector assembly or poor cable laying can be such that they are not detected through an analysis based on worst case limit values because the errors initially cause only a minor disturbance of the transmission quality.